Semiconductor integrated circuit device

ABSTRACT

A semiconductor integrated circuit device provided with a plurality of power supply wire layers including a first potential power supply wire and a second potential power supply wire formed in different layers. At least one capacitor contact wire extends from one of the first and second potential power supply wires toward the other one of the first and second potential power supply wires so as to form a capacitor between each capacitor contact wire and its surrounding wires.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No. 2006-040340, filed on Feb. 17, 2006, the entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to a semiconductor integrated circuit device including decoupling capacitors for reducing power supply noise.

In a semiconductor integrated circuit device, decoupling capacitors may be formed between power supply wires to reduce power supply noise. A decoupling capacitor can be formed with a gate oxide film. However, an increase in standby current, which results from gate leak current, cannot be ignored. Accordingly, decoupling capacitors are formed by using capacitors between power supply wires.

Various examples of decupling capacitors formed between power supply wires have been proposed.

Japanese Laid-Open Patent Publication No. 2002-324841 describes a contact wire for connecting high potential power supply wires and a contact wire for connecting lower potential power supply wires. A capacitor is formed on an interlayer insulative film located between the contact wires.

Japanese Laid-Open Patent Publication No. 2001-177056 describes a high potential power supply wire and a low potential power supply wire included in multiple layers of power supply wires. The high potential power supply wire and the low potential power supply wire each include a capacitor power supply wire extending in a planar direction and a thicknesswise direction of a substrate.

Japanese Laid-Open Patent Publication No. 2003-249559 describes multiple layers of power supply wires in which each layer includes a high potential power supply wire and a low potential power supply wire that are parallel and adjacent to each other. The wires of an upper layer traverse the wires of a lower layer. A contact wire connects power supply wires, which are located in the upper layer and the lower layer and have the same potential.

Japanese Laid-Open Patent Publication No. 2004-241762 describes multiple layers of power supply wires in which each layer includes a high potential power supply wire and a low potential power supply wire that are parallel and adjacent to each other. The wires of an upper layer are parallel to the wires of a lower layer.

SUMMARY OF THE INVENTION

In the power supply wire of Japanese Laid-Open Patent Publication No. 2002-324841, the contact wire forming the. capacitor is formed only on an end portion of each power supply wire. Thus, the number of contact wires is limited and there are not enough decupling capacitors.

In the configuration described in Japanese Laid-Open Patent Publication No. 2001-177056, the capacitance between layers is dependent on the distance between the layers. Thus, when the distance between layers increases, sufficient capacitance cannot be obtained. Further, the distance between a capacitor wire, which extends from each power supply wire, and a contact hole, which connects power supply wires having the same potential in the upper and lower layers, increases. Thus, the responsiveness of the capacitor wire to changes in the power supply voltage is poor, and the prevention of power supply voltage fluctuation cannot be ensured.

In the configuration described in Japanese Laid-Open Patent Publication No. 2003-249559, capacitors, which are formed between the power supply wires of the upper and lower layers, are formed only at locations where the power supply wires of the upper and lower layers traverse one another. Thus, there are not enough decoupling capacitors.

In the configuration described in Japanese Laid-Open Patent Publication No. 2004-241762, capacitors are formed only between power supply wires extending parallel to each other in the same layer. Thus, three are not enough decoupling capacitors.

One aspect of the present invention is a semiconductor integrated circuit device provided with a plurality of power supply wire layers including a first potential power supply wire and a second potential power supply wire formed in different layers. At least one capacitor contact wire extends from one of the first and second potential power supply wires toward the other one of the first and second potential power supply wires so as to form a capacitor between each capacitor contact wire and its surrounding wires.

Other aspects and advantages of the present invention will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, together with objects and advantages thereof, may best be understood by reference to the following description of the presently preferred embodiments together with the accompanying drawings in which:

FIGS. 1, 2, and 3 are respectively a perspective view, an exploded perspective view, and a plan view showing a power supply wire layer according to a first embodiment of the present invention;

FIG. 4 is a perspective view showing a capacitor contact wire;

FIGS. 5 and 6 are respectively a perspective view and a plan view showing a power supply wire layer according to a second embodiment of the present invention;

FIGS. 7 and 8 are respectively a perspective view and a plan view showing a power supply wire layer according to a third embodiment of the present invention;

FIGS. 9, 10, and 11 are respectively a perspective view showing a power supply wire layer according to a fourth embodiment of the present invention, a plan view showing a first power supply wire layer, and a plan view showing a second power supply wire layer;

FIGS. 12 and 13 are respectively a plan view showing a first power supply wire according to a fifth embodiment of the present invention and a plan view showing a second power supply wire layer;

FIGS. 14, 15, and 16 are respectively a plan view of a first power supply wire layer, a plan view of a second power supply wire layer, and a perspective view of a power supply wire layer;

FIG. 17 is a perspective view showing a power supply wire layer according to a seventh embodiment of the present invention; and

FIGS. 18 and 19 are respectively a perspective view and a plan view of a power supply wire layer according to an eighth embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A semiconductor integrated circuit device according to a first embodiment of the present invention will now be discussed. As shown in FIG. 1, the semiconductor integrated circuit device includes a plurality of power supply wire layers in which decoupling capacitors are formed. The power supply wire layers include a first power supply wire layer 1 and a second power supply wire layer 4.

The first power supply wire layer 1 includes high potential wires (VDD) 2 a and low potential wires (VSS) 3 a of predetermined lengths. The second power supply wire layer 4 includes high potential wires (VDD) 2 b and low potential wires (VSS) 3 b of predetermined lengths.

The high potential wires 2 a and 2 b and the low potential wires 3 a and 3 b are formed on a substrate and are connected to main power supply wires (not shown) formed on the substrate by, for example, contact wires (not shown).

The shapes of the high potential wires 2 a and 2 b and the low potential wires 3 a and 3 b will now be described with reference to FIGS. 2 and 3.

FIG. 2 shows an example of a power supply wire layer having a triple-layer structure. Each of the high potential wires 2 a and 2 b and the low potential wires 3 a and 3 b has a bent middle portion so as to extend in a meandering manner.

In the first power supply wire layer 1, the high potential wires 2 a and the low potential wires 3 a include linear portions that are parallel to one another. In the second power supply wire layer 4, the high potential wires 2 b and the low potential wires 3 b include linear portions that are parallel to one another. Accordingly, a linear portion of a high potential wire is parallel to a linear portion of a low potential wire to form a capacitor.

The high potential wires 2 a of the first power supply wire layer 1 and the high potential wires 2 b of the second power supply wire layer 4 meander in an alternating manner with respect to one another. The bent middle portion of each high potential wire 2 a in the first power supply wire layer 1 is located above the bent middle portion of a corresponding high potential wire 2 b in the second power supply wire layer 4. The linear portions of each high potential wire 2 a in the first power supply wire layer 1 is located above the linear portions of corresponding low potential wires 3 b in the second power supply wire layer 4. The linear portions of each high potential wire 2 a in the first power supply wire layer 1 is not located above the linear portions of corresponding high potential wires 2 b in the second power supply wire layer 4. In other words, each high potential wire 2 a has a mirror image relationship with the underlying high potential wire 2 b. Thus, when each high potential wire 2 a is reversed on a plane (M1 or M2 in FIG. 3) lying along an axis (e.g., 5 a) that extends through the bent middle portion, the reversal has a shape identical to the high potential wire 2 b located below the high potential wire 2 a. The first low potential wires 3 a of the first power supply wire layer 1 and the low potential wires 3 b of the second power supply wire layer 4 have the same relationship as the high potential wires 2 a and 2 b.

The bent middle portion of each high potential wire 2 a in the first power supply wire layer 1 and the bent middle portion of the corresponding high potential wire 2 b in the second power supply wire layer 4 are connected to each other by a contact wire 5 a. In the same manner, the bent middle portion of each low potential wire 3 a in the first power supply wire layer 1 and the bent middle portion of the corresponding low potential wire 3 b in the second power supply wire layer 4 are connected to each other by a contact wire 5 b. The contact wires 5 a connecting the high potential wires 2 a and 2 b extend parallel to the contact wires 5 b connecting the low potential wires 3 a and 3 b.

The linear portion of each low potential wire 3 b in the second power supply wire layer 4 is located below the linear portion of the corresponding high potential wire 2 a in the first power supply wire layer 1. The linear portion of each high potential wire 2 b in the second power supply wire layer 4 is located below the linear portion of the corresponding low potential wire 3 a in the first power supply wire layer 1.

Capacitor contact wires, which do not connect the high potential wires 2 a and the low potential wires 3 b, and capacitor contact wires, which do not connect the low potential wires 3 a and the high potential wires 2 b, are arranged between the first power supply wire layer 1 and the second power supply wire layer 4. Each capacitor contact wire (capacitor formation wire) is connected to only a corresponding one of the high and low potential wires.

In the example of FIG. 1, a capacitor contact wire 6 a extends downward from one end of each high potential wire 2 a in the first power supply wire layer 1. A capacitor contact wire 6 b extends downward from an end of each low potential wire 3 a in the first power supply wire layer 1. A capacitor contact wire 6 c extends downward from a middle position in the linear portion of each high potential wire 2 a in the first power supply wire layer 1. A capacitor contact wire 6 d extends downward from a middle position in the linear portion of each low potential wire 3 a in the first power supply wire layer 1.

A capacitor contact wire 6 e extends upward from a middle position in the linear portion of each low potential wire 3 b in the second power supply wire layer 4. The capacitor contact wire 6 e is located between the corresponding capacitor contact wires 6 a and 6 c. A capacitor contact wire 6 f extends upward from a middle position in the linear portion of each high potential wire 2 b in the second power supply wire layer 4. The capacitor contact wire 6 f is located between the corresponding capacitor contact wires 6 b and 6 d.

In this structure, each capacitor contact wire is surrounded by other capacitor contact wires. For example, each capacitor contact wire 6 f is surrounded by the capacitor contact wires 6 b, 6 d, and 6 e. Each capacitor contact wire 6 e is surrounded by the capacitor contact wires 6 a, 6 c, and 6 f.

The operation of the capacitor contact wire will now be discussed with reference to FIG. 4.

A plurality of capacitor contact wires 6 f and a plurality of capacitor contact wires 6 g, which respectively extend from the high potential wire 2 and the low potential wire 3, are alternately arranged. In this case, a capacitor is formed between the capacitor contact wires 6 f and 6 g. Further, a capacitor is formed between the end of each of the capacitor contact wires 6 f and 6 g and the opposing one of the high potential wire 2 and the low potential wire 3.

The semiconductor integrated circuit device of the first embodiment has the advantages described below.

(1) In each power supply wire layer, decoupling capacitors are formed between parts of the high potential wires 2 a and 2 b and parts of the low potential wires 3 a and 3 b. The high potential wires 2 a and 2 b and the low potential wires 3 a and 3 b are laid out parallel to one another.

(2) The capacitor contact wires 6 a to 6 e form a plurality of decoupling capacitors between the high potential wires 2 a and low potential wires 3 a of the first power supply wire layer 1 and the high potential wires 2 b and low potential wires 3 b of the second power supply wire layer 4.

(3) A plurality of decoupling capacitors are formed between the capacitor contact wires 6 a to 6 e.

(4) The capacitor contact wires 6 a to 6 e are each surrounded by capacitor contact wires having a different power supply voltage, or potential. This easily obtains sufficient capacitance.

(5) The high potential wires 2 a and 2 b and the low potential wires 3 a and 3 b each have a bent middle portion. The bent middle portion of each high potential wire 2 a locally overlaps the bent middle portion of the underlying high potential wire 2 b. Accordingly, the middle portion of each high potential wire 2 a in the first power supply wire layer 1 and the middle portion of the corresponding high potential wire 2 b in the second power supply wire layer 4 are connected by the contact wire 5 a linearly by the shortest distance. Further, the bent middle portion of each low potential wire 3 a locally overlaps the bent middle portion of the underlying low potential wire 3 b. Accordingly, the middle portion of each low potential wire 3 a in the first power supply wire layer 1 and the middle portion of the corresponding low potential wire 3 b in the second power supply wire layer 4 are connected by the contact wire 5 b linearly by the shortest distance.

(6) The contact wires 5 a connect the bent middle portions of the high potential wires 2 a in the first power supply wire layer 1 to the bent middle portions of the corresponding high potential wires 2 b in the second power supply wire layer 4. The contact wires 5 b connect the bent middle portions of the low potential wires 3 a in the first power supply wire layer 1 to the bent middle portions of the corresponding low potential wires 3 b in the second power supply wire layer 4. This reduces the distance from the contact wires 5 a and 5 b to the portions where the decoupling capacitors act. Thus, the responsiveness of the decoupling capacitors is improved, and the power supply noise is effectively absorbed.

(7) The above structure forms decoupling capacitors having sufficient capacitance in a semiconductor integrated circuit.

A second embodiment will now be described with reference to FIGS. 5 and 6.

A semiconductor integrated circuit device of the second embodiment includes a first power supply wire layer 1 having a linear high potential wire 7 a and a low potential wire 8 a. A second power supply wire layer 4 includes a high potential wire 7 b and a low potential wire 8 b.

The high potential wire 7 b is located below the high potential wire 7 a. The low potential wire 8 b is located below the low potential wire 8 a. A plurality of contact wires 9 a connect the high potential wires 7 a and 7 b at predetermined intervals. A plurality of contact wires 9 b connect the low potential wires 8 a and 8 b at predetermined intervals.

Branch wires 10 a extend from the high potential wire 7 a toward the low potential wire 8 a. Branch wires 11 a extend from the low potential wire 8 a toward the high potential wire 7 a. The branch wires 10 a and 11 a are alternately arranged. Further, capacitors are formed between the branch wires 10 a and 11 a.

Branch wires 10 b extend from the high potential wire 7 b toward the low potential wire 8 b. Branch wires 11 b extend from the low potential wire 8 b toward the high potential wire 7 b. The branch wires 10 b and 11 b are alternately arranged. Further, capacitors are formed between the branch wires 10 b and 11 b.

The branch wires 11 b extending from the low potential wire 8 b are located below the branch wires 10 a of the first power supply wire layer 1. The branch wires 10 b extending from the high potential wire 7 b are located below the branch wires 11 a of the first power supply wire layer 1.

Capacitor contact wires 12 a extend downward from distal ends of the branch wires 10 a. Capacitor contact wires 12 b extend downward from distal ends of the branch wires 11 a. The capacitor contact wires 12 a and 12 b are alternately arranged. A capacitor is formed between adjacent ones of the capacitor contact wires 12 a and 12 b.

The capacitor contact wires 12 a have distal ends spaced from the underlying branch wires 11 b by a predetermined distance. The capacitor contact wires 12 b have distal ends spaced from the underlying branch wires 10 b by a predetermined distance. A capacitor is formed between the distal ends of the capacitor contact wires 12 a and 12 b and the underlying branch wires 11 b and 10 b.

The semiconductor integrated circuit device of the second embodiment has the advantages described below.

(1) Capacitors are formed between the branch wires 10 a and 11 a of the first power supply wire layer 1. Further, capacitors are formed between the branch wires 10 b and 11 b of the second power supply wire layer 4.

(2) A capacitor is formed between adjacent ones of the capacitor contact wires 12 a and 12 b.

(3) Capacitors are formed between the distal ends of the capacitor contact wires 12 a and 12 b and the opposing branch wires 11 b and 10 b.

(4) The distance from the contact wires 9 a, which connect the high potential wires 7 a and 7 b, and the contact wires 9 b, which connect the low potential wires 8 a and 8 b, to the portions where the capacitors are formed may be reduced. This improves the responsiveness of the decoupling capacitors and effectively absorbs the power supply noise.

(5) The above structure forms decoupling capacitors having sufficient capacitance.

A third embodiment will now be discussed with reference to FIGS. 7 and 8.

A semiconductor integrated circuit device of the third embodiment includes a plurality of relatively long branch wires and a plurality of capacitor contact wires respectively formed on the branch wires. For the sake of brevity, like or same reference numerals are given to those components that are the same as the corresponding components of the second embodiment.

Branch wires 13 a, 13 b, 14 a, and 14 b are longer than the branch wires 10 a, 10 b, 11 a, and 11 b of the second embodiment. Three capacitor contact wires 15 a are formed on each branch wire 13 a, and three capacitor contact wires 15 b are formed on each branch wire 14 a.

In the semiconductor integrated circuit device of the third embodiment, the capacitor contact wires 15 a and 15 b are increased in number. This further increases the decoupling capacitors in comparison with the second embodiment.

A fourth embodiment will now be discussed with reference to FIGS. 9 to 11.

In the third embodiment, three capacitor contact wires 15 a are formed on each branch wire 13 a, and three capacitor contact wires 15 b are formed on each branch wire 14 a. In the fourth embodiment, capacitor contact wires extend from each of the branch wires 13 a, 13 b, 14 a, and 14 b of the first power supply wire layer 1 and the second power supply wire layer 4. For the sake of brevity, like or same reference numerals are given to those components that are the same as the corresponding components of the third embodiment.

In the first power supply wire layer 1, two capacitor contact wires 15 c extend downward from each branch wire 13 a, and two capacitor contact wires 15 d extend downward from each branch wire 14 a. In the second power supply wire layer 4, one capacitor contact wire 15 e extends upward from each branch wire 13 b, and one capacitor contact wire 15 f extends upward from each branch wire 14 b. Each of the capacitor contact wires 15 e and 15 f is arranged between the corresponding capacitor contact wires 15 c and 15 d.

In the semiconductor integrated circuit device of the fourth embodiment, capacitors are formed between the capacitor contact wires 15 c, 15 f, 15 d, and 15 e. Thus, decoupling capacitors are further increased in number compared with the third embodiment.

A fifth embodiment will now be discussed with reference to FIGS. 12 and 13.

In comparison with the fourth embodiment, the capacitor contact wires formed on each branch wire is increased in number in the fifth embodiment. For the sake of brevity, like or same reference numerals are given to those components that are the same as the corresponding components of the fourth embodiment.

As shown in FIG. 12, a high potential wire 7 a and a low potential wire 8 a of the first power supply wire layer 1 are linear. The wires 7 a and 8 a respectively include a plurality of branch wires 16 a and 17 a. As shown in FIG. 13, a high potential wire 7 b and a low potential wire 8 b of the second power supply wire layer 4 are linear. The wires 7 b and 8 b respectively include a plurality of branch wires 16 b and 17 b. The area of the branch wires 16 a, 16 b, 17 a, and 17 b is greater than that of the branch wires 13 a, 13 b, 14 a, and 14 b of the fourth embodiment.

In the first power supply wire layer 1, the branch wires 16 a each include, for example, six capacitor contact wires 18 a extending downward, and the branch wires 17 a each include, for example, six capacitor contact wires 18 b extending downward. The branch wires 17 b and 16 b of the second power supply wire layer 4 respectively oppose the branch wires 16 a and 17 a. The branch wires 17 b each include, for example, six capacitor contact wires 18 c extending upward, and the branch wires 16 b each include, for example, six capacitor contact wires 18 d extending upward. The capacitor contact wires 18 a and 18 b and the capacitor contact wires 18 c and 18 d are alternately arranged (refer to FIG. 4).

In the semiconductor integrated circuit device of the fifth embodiment, a capacitor is formed between the capacitor contact wires 18 a to 18 b of which the number is greater than that in the fourth embodiment. Thus, decoupling capacitors are increased in number compared with the fourth embodiment.

A sixth embodiment will now be discussed with reference to FIGS. 14 to 16.

In the second to fifth embodiments, the formation of the capacitor contact wires become difficult when the distance of the high potential and low potential wires in the first power supply wire layer 1 from the high potential and low potential wires in the second power supply wire layer 4 becomes short. In the sixth embodiment, the formation of decoupling capacitors with capacitor contact wires is ensured even if the distance between the first power supply wire layer 1 and the second power supply wire layer 4 is short. For the sake of brevity, like or same reference numerals are given to those components that are the same as the corresponding components of the fifth embodiment.

As shown in FIG. 14, a plurality of branch wires 19 a are formed on the high potential wire 7 a of the first power supply wire layer 1. A plurality of branch wires 20 a are formed on the low potential wire 8 a in the first power supply wire layer 1. As shown in FIG. 15, a plurality of branch wires 19 b are formed on the high potential wire 7 b of the second power supply wire layer 4. A plurality of branch wires 20 b are formed on the low potential wire 8 b in the second power supply wire layer 4.

The branch wires 19 a and the underlying branch wires 20 b will now be discussed with reference to FIG. 16. For example, eight capacitor contact wires 21 a extend upward from the edges of each branch wire 19 a. A hole 22 is formed in the center of each branch wire 19 a.

A capacitor contact wire 21 b extends upward from the center of each branch wire 20 b. The corresponding hole 22 receives the capacitor contact wire 21 b. The branch wires 20 a of the first power supply wire layer 1 and the branch wires 19 b of the second power supply wire layer 4 are formed in a manner similar to the branch wires 19 a and 20 b.

In the semiconductor integrated circuit device of the sixth embodiment, a capacitor is formed between the capacitor contact wire 21 b and the surrounding capacitor contact wires 21 a. Accordingly, even if the distance between the first power supply wire layer 1 and the second power supply wire layer 4 is short, capacitor contact wires may be formed on branch wires.

A seventh embodiment will now be discussed with reference to FIG. 17.

In the seventh embodiment, a branch wire 23 a, which has a first potential, is located in a narrow space between branch wires 23 b and 23 c, which have a second potential. A plurality of capacitor contact wires 24 a extend upward from the edges of the branch wire 23 b. A plurality of capacitor contact wires 24 b extend downward from the edges of the branch wire 23 c.

A hole 25 extends through the center of each of the branch wires 23 b and 23 c. Capacitor contact wire 24 c and 24 d respectively extend upward and downward from the upper and lower surfaces in the center of the branch wire 23 a. The holes of the branch wires 23 b and 23 c respectively receive the capacitor contact wires 24 c and 24 d.

In the semiconductor integrated circuit device of the seventh embodiment, a capacitor is formed between the capacitor contact wires 24 c and the surrounding capacitor contact wires 24 a. Further, a capacitor is formed between the capacitor contact wire 24 d and the surrounding capacitor contact wires 24 b. Accordingly, capacitor contact wires are formed on the branch wires even in a triple-layer structure in which the space between the high potential and low potential power supply wires is narrow.

An eighth embodiment will now be discussed with reference to FIGS. 18 and 19.

Referring to FIG. 18, high potential wires 26 a and low potential wires 27 a are located in a first power supply wire layer, and high potential wires 26 b and low potential wires 27 b are located in a second power supply wire layer. The high potential wires 26 a and the low potential wires 27 a extend in a first direction, and the high potential wires 26 b and the low potential wires 27 b extend in a second direction, which is orthogonal to the first direction.

Referring to FIG. 19, the high potential wires 26 a are connected to a plurality of contact wires 28 at a plurality of first grid points, or intersecting points with the high potential wires 26 b when viewed from above. The low potential wires 27 a are connected to a plurality of contact wires 29 at a plurality of first grid points, or intersecting points with the low potential wires 27 b when viewed from above.

A plurality of capacitor contact wires 30 a are respectively formed at a plurality of second grid points, or intersecting points between the high potential wires 26 a and the low potential wires 27 b. The capacitor contact wires 30 a extend from the high potential wires 26 a toward the low potential wires 27 b. A plurality of capacitance contact wires 30 b are respectively formed at a plurality of second grid points, or intersecting points between the high potential wires 26 b and the low potential wires 27 a. The capacitor contact wires 30 b extend from the high potential wires 26 b toward the low potential wires 27 a.

In the semiconductor integrated circuit device of the eighth embodiment, a capacitor is formed between the capacitor contact wires 30 a and the adjacent contact wires 29 and low potential wires 27 b. Further, a capacitor is formed between the capacitor contact wires 30 b and the adjacent contact wires 29 and low potential wires 27 a.

Accordingly, the capacitor contact wires 30 a and 30 b may be formed in large numbers to increase the decoupling capacitor even when the high potential wires 26 b and the low potential wires 27 b in the first power supply wire layer 1 intersect with the high potential wires 26 b and the low potential wires 27 b in the second power supply wire layer 4.

In each of the above embodiments, the power supply wire layers may be further increased in number.

It should be apparent to those skilled in the art that the present invention may be embodied in many other specific forms without departing from the spirit or scope of the invention. Therefore, the present examples and embodiments are to be considered as illustrative and not restrictive, and the invention is not to be limited to the details given herein, but may be modified within the scope and equivalence of the appended claims. 

1. A semiconductor integrated circuit device comprising: a plurality of power supply wire layers including a first potential power supply wire and a second potential power supply wire formed in different layers; and at least one capacitor contact wire extending from one of the first and second potential power supply wires toward the other one of the first and second potential power supply wires and forming a capacitor between each capacitor contact wire and its surrounding wires.
 2. The semiconductor integrated circuit device according to claim 1, wherein: the power supply wire layers each include a plurality of meandered first potential power supply wires, each having a bent middle portion, and a plurality of meandered second potential power supply wires, each having a bent middle portion, with the plurality of meandered first potential power supply wires and the plurality of meandered second potential power supply wires arranged alternately in each of the power supply wire layers; the plurality of power supply wire layers include a first layer and an adjacent second layer; the bent middle portions of the first and second potential power supply wires in the first layer and the bent middle portions of the power supply wires having the same potential in the second layer are opposed to each other and connected to each other by a plurality of contact wires; the first potential power supply wires and the second potential power supply wires have portions exclusive of the bent middle portions that are respectively opposed to the power supply wires having different potentials in the second layer; and the at least one capacitor contact wire includes a plurality of capacitor contact wires extending from each of the first and second potential power supply wires in the first layer toward the power supply wires having different potentials in the second layer.
 3. The semiconductor integrated circuit device according to claim 2, wherein the at least one capacitor contact wire includes: a plurality of first capacitor contact wires extending from each of the first and second potential power supply wires in the first layer toward the power supply wires having different potentials in the second layer; and a plurality of second capacitor contact wires extending from each of the first and second potential power supply wires in the second layer and arranged alternately with the plurality of first capacitor contact wires.
 4. The semiconductor integrated circuit device according to claim 2, wherein the at least one capacitance contact wire includes: a plurality of capacitor contact wires extending from the portions of the first and second potential power supply wires exclusive of the bent middle portions in the first layer toward the portions of the power supply wires exclusive of the bent middle portions having different potentials in the second layer.
 5. The semiconductor integrated circuit device according to claim 1, wherein: the power supply wire layers each include a plurality of first potential power supply wires and a plurality of second potential power supply wires; the first potential power supply wires and the second potential power supply wires are alternately arranged in each of the power supply wire layers; each of the first potential power supply wires and each of the second potential power supply wires in each of the power supply wire layers includes a plurality of branch wires spaced from each other by a predetermined interval, the branch wires of the first potential power supply wires being alternately arranged with the branch wires of the second potential power supply wires; the plurality of power supply wire layers include a first layer and an adjacent second layer; the branch wires in the first layer are opposed to the branch wires of the power supply wires having a different potential in the second layer; and the at least one capacitor contact wire includes a plurality of capacitor contact wires extending from the branch wires in the first layer toward the plurality of branch wires of the power supply wires having a different potential in the second layer.
 6. The semiconductor integrated circuit device according to claim 5, wherein the at least one capacitor contact wire includes a plurality of capacitor contact wires extending from each of the branch wires.
 7. The semiconductor integrated circuit device according to claim 6, wherein the capacitor contact wires extending from the branch wires in the first layer are arranged alternately with the plurality of capacitor contact wires extending from the branch wires in the second layer.
 8. The semiconductor integrated circuit device according to claim 1, wherein: the power supply wire layers each include a plurality of first potential power supply wires and a plurality of second potential power supply wires; the first potential power supply wires and the second potential power supply wires are alternately arranged in each of the power supply wire layers; each of the first potential power supply wires and each of the second potential power supply wires in each of the power supply wire layers includes a plurality of branch wires spaced from each other by a predetermined interval, the branch wires of the first potential power supply wires being alternately arranged with the branch wires of the second potential power supply wires; the plurality of power supply wire layers include a first layer and an adjacent second layer; the branch wires in the first layer are opposed to the branch wires of the power supply wires having a different potential in the second layer; and the branch wires in the first layer each includes a central hole; and the at least one capacitor contact wire includes: a plurality of first capacitor contact wires surrounding the central hole of each of the branch wires in the first layer and extending away from the corresponding branch wire in the second layer; and a second capacitor contact wire extending from each of the branch wires in the second layer and received by the central hole of the corresponding branch wire in the first layer.
 9. The semiconductor integrated circuit device according to claim 1, wherein: the plurality of power supply wire layers include a first layer and an adjacent second layer, the first and second potential power supply wires in the first layer and the first and second potential power supply wires in the second layer respectively defining a plurality of first grid points, and the first and second potential power supply wires in the first layer and the second and first potential power supply wires in the second layer respectively defining a plurality of second grid points; the first and second potential power supply wires in the first layer are respectively connected to the power supply wires having the same potential in the second layer at the first grid points; and the at least one of the capacitor contact wires includes a plurality of capacitor contact wires extending from one of the power supply wires in one of the first and second layers toward one of the power supply wires having a different potential in the other one of the first and second layers.
 10. A semiconductor integrated circuit device comprising: a plurality of power supply wire layers including a first layer and an adjacent second layer, with the first layer and the second layer each including a plurality of first potential power supply wires and a plurality of second power supply wires, wherein the first potential power supply wires in the first layer form an intralayer capacitor with the second potential power supply wires in the first layer; and a plurality of capacitor contact wires extending parallel to one another between the first layer and the second layer, each capacitor contact wire forming a capacitor with its surrounding capacitor contact wires and forming a capacitor with each of the power supply wires in the first layer and the power supply wires having different potentials in the second layer.
 11. The semiconductor integrated circuit device according to claim 10, wherein, each of the capacitor contact wires includes: a basal end connected to either one of the first potential power supply wire and the second potential power supply wire in the first layer; and a distal end separated from the other one of the first potential power supply wire and the second potential power supply wire in the second layer, a capacitor being formed between the distal end of each capacitor contact wire and the other one of the first potential power supply wire and the second potential power supply wire in the second layer.
 12. The semiconductor integrated circuit device according to claim 11, wherein the plurality of capacitor contact wires include: a plurality of capacitor contact wires having a first potential and extending from the first potential power supply wires in the first layer and the second layer; and a plurality of capacitor contact wires having a second potential and extending from the second potential power supply wires in the first layer and the second layer, wherein each of the capacitor contact wires is surrounded by a plurality of the capacitor contact wires having different potentials, and each of the capacitor contact wires forms a capacitor with the plurality of surrounding capacitor contact wires. 